add ability to remove user and add task depndencies closes #69

sql/tasks.sql

@@ -16,19 +16,25 @@ create table if not exists tasks (
 
     result text default '',
     extra_task_info text default '',
-    
+
     -- -1: user said task is wrong
     --  0: no user input
     --  1: user said task is ok
     user_confirmed integer default 0,
-    
+
     -- Tells the user if the file has been already compacted into
     --  embendings
     compacted integer default 0,
-        
+
     -- TODO move the training tasks to here
     --  1: Classification
     task_type integer,
 
     created_on timestamp default current_timestamp
-)
+);
+
+create table if not exists tasks_dependencies (
+    id uuid primary key default gen_random_uuid(),
+    main_id uuid references tasks (id) on delete cascade not null,
+    dependent_id uuid references tasks (id) on delete cascade not null
+);